MERV and LEED?

MERV stands for "minimum efficiency reporting value". MERV ratings were created by ASHRAE (American Society of Heating Refrigeration and Air Conditioning Engineers") to quantify the effectiveness of air filters (aka "filtration media") in buildings. MERV uses a scale from 1-20... The lower the MERV rating, the worse the filter (eg. the larger the size of material or particulate matter can flow through without being stopped by the filter).

For instance, a heating/air conditioning system in a home with a MERV filter of 4 might filter large particulate matter such as bugs... but it wouldn't stop dust mites from getting through.

LEED counts indoor air quality as a major category of green building design. LEED v4 requires filtration media with a MERV rating of 13 to comply with EQ credit Enhanced Indoor Air Quality Strategies. LEED v4 requires filtration media with a MERV rating of 11 or higher for compliance with EQ credit Minimum Indoor Air Quality Performance. LEED v4 also advises to use filtration media with a MERV rating of 8 if operating any permanently installed air-handling equipment in a building while seeking to comply with EQ credit Construction Indoor Air Quality Management Plan.

In contrast to MERV, HEPA stands for high efficiency particulate arrestance"... HEPA filters are defined by the United States Department of Energy (DOE) to remove 99.97% of airborne particles 0.3 micrometers in diameter... In other words HEPA filters are used in laboratories and clean rooms to capture the REALLY REALLY SMALL STUFF!